So in Eclipse, I’m aware that if I have included sources in maven dependencies, as well as the JDK, I can open a type to see it’s implementation (Type Ctrl+T):

This is great for .java classes, but I don’t appear to have any quick shortcut to open resources other than java .classes. For instance, I do some Clojure and JRuby, which both .jar up their sources, which are generally just the sources themselves.
No. As per my knowledge, there are no keyboard shortcuts in eclipse to open resource file from jar. Only classes can be accessed by
Ctrl+T. I always have to use package explorer to navigate contents in jar file.